1. Field of the Invention
The present invention relates to an apparatus for improving the radio wave transmitting capability. Particularly, the present invention relates to an apparatus for inhibiting cross talk under a difference mode, in which undesired cross talk due to the adjacency and non-uniformness of the untwisted portion are eliminated when untwisting the UTP (unshielded twisted pair) cables to insert the UTP cables into plug holes. More specifically, in four pairs which are liable to generate cross talk due to their adjacency, artificial patterns are disposed on the front and rear faces of a PCB in such a manner that an effect same as insertion of a spiral capacitor should be produced, so that the cross talk in the interfering two lines would meet the regulated value.
2. Description of the Prior Art
Generally, if the widely used twisted pair cable is connected to a balanced circuit, then theoretically the cross talk will never be produced.
However, in actuality, the magnitude of the cross talk very sensitively respond to the distance between the impeded line and the impeding line where the twisting rate of the twisted pair cable is not constant.
As the conventionally used signal transmitting cables, there are coaxial cables, fiber optics cables and UTP cables.
In the coaxial cables, when a problem occurs, it is difficult to solve. In the fiber optics cables, the cost is high, and the installation and maintenance are difficult. Therefore, the UTP cables which are convenient and easy to use are widely employed.
In the UTP cables, there is no problem at the transmission speed of LAN (local area network), i.e., at 10 Mb/s. However, at 100 Mb/s which is to be applied in the future, problems such as cross talk, attenuation loss, return loss and the like occur at the near end. The limit values for the above problems are regulated in the international standards such as ISO/IEC.